Just a thought that maybe a squirt of heavy oil to the half nut dovetails might improve the feel on the lever.
It is a place that is difficult to access and might be neglected on lube day.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Help with Lathe Thread Dial
- Thread starter macardoso
- Start date
It is a place that is difficult to access and might be neglected on lube day.
I was having trouble on my old South Bend thread dial after I took it apart to clean and oil.
The dial will move on the shaft. If the numbers do not correlate with the timing on the lead screw the dial will need to be loosened and adjusted to line up with the corresponding fit between the half nuts and the lead screw.
In other words, when the half nuts were engaged, the dial never aligned with a number, always off by a matter of degrees until I corrected it.
Does this make sense at all?
Made all the difference in the world.
The dial will move on the shaft. If the numbers do not correlate with the timing on the lead screw the dial will need to be loosened and adjusted to line up with the corresponding fit between the half nuts and the lead screw.
In other words, when the half nuts were engaged, the dial never aligned with a number, always off by a matter of degrees until I corrected it.
Does this make sense at all?
Made all the difference in the world.
If your lathe has a metric leadscrew (which it sounds like it does) then you must leave halfnut engaged just like threading metric with an american leadscrew If threading to a shoulder you can disengage as long as you reengage on same line without skipping it and then reversing lathe
Edit: sorry, i didn't realize you were trying to cut english threads, not metric!
Did you ever figure this out? On my similar lathe (Grizzly G9249) the manual says "To cut metric threads, the half nuts must be left continually engaged once the start point has been selected and the half nut is initially engaged (thread dial cannot be used).
Did you ever figure this out? On my similar lathe (Grizzly G9249) the manual says "To cut metric threads, the half nuts must be left continually engaged once the start point has been selected and the half nut is initially engaged (thread dial cannot be used).
Yeah, I believe the threading dial and chart is accurate. I found it easy to miss the mark on the dial and drop into the thread on the lead screw only partially. This ruins the thread. I engraved a more accurate and crisp mark on the outside of the thread dial to line up against and learned to snap the threading lever down more assertively once it was in position rather than gently pulling the lever just before the tick and “falling” into the thread as I was taught.
I’ve been doing a fair bit of single point threading recently with no issues other than operator error.
With metric threading I do not use the threading dial.
I’ve been doing a fair bit of single point threading recently with no issues other than operator error.
With metric threading I do not use the threading dial.
What little experience I have had with my machine, I also find it easy to partially engage the threading lever (half nut). Perhaps on an american machine, the lever would "fall" into place, but not mine! Cheers
I learned to thread on a new big South Bend lathe (14x60” maybe?). The threading lever was super crisp and I never missed a thread. My Enco is in great shape but just feels sloppy in comparison. Granted I paid 1/20th of what that South Bend costs.
Although we can get used to the peculiarities of a machine it would unnerve me to lack 'feel' on the half nut lever.
Would there be any point for you to disassemble the half nut mechanism and make sure everything is optimal? There is a dove tail and gib adjustment on mine. My lathe is an entry level budget lathe and it needed/needs to be checked out, cleaned and adjusted in every way possible to work right.
I agree with you. Unfortunately I have had it apart and haven't had much luck in getting it to engage more crisply. My halfnuts are in perfect condition and my lead screw is as well. I keep the lathe very clean, especially the screw. One issue with the lathe design is that the interlock for the power feed has a return spring that acts against the threading lever. I think that, combined with the slope of the screw wall, can drive the halfnuts open a little as it runs (unless I keep downward pressure on the lever) and can make it less crisp of an engagement.